Forrest Mims, Radio Shack, and the Notebooks that Launched a Thousand Careers
There was a time when Radio Shack offered an incredible variety of supplies for the electronics hobbyist. In the back of each store, past the displays of Realistic 8-track players, Minimus-7 speakers, Patrolman scanners, and just beyond the battery bin where you could cash in your “Battery of the Month Club” card for a fresh, free 9-volt battery, lay the holy of holies — the parts. Perfboard panels on hinges held pegs with cards of resistors for 49 cents, blister packs of 2N2222 transistors and electrolytic capacitors, and everything else you needed to get your project going. It was a …read more
Understanding The Quartz Crystal Resonator
Accurate timing is one of the most basic requirements for so much of the technology we take for granted, yet how many of us pause to consider the component that enables us to have it? The quartz crystal is our go-to standard when we need an affordable, known, and stable clock frequency for our microprocessors and other digital circuits. Perhaps it’s time we took a closer look at it.
The first electronic oscillators at radio frequencies relied on the electrical properties of tuned circuits featuring inductors and capacitors to keep them on-frequency. Tuned circuits are cheap and easy to produce, …read more
Microfluidics “Frogger” is a Game Changer for DIY Biology
See those blue and green dots in the GIF? Those aren’t pixels on an LCD display. Those are actual drops of liquid moving across a special PCB. The fact that the droplets are being manipulated to play a microfluidics game of “Frogger” only makes OpenDrop v 2.0 even cooler.
Lab biology is mainly an exercise in liquid handling – transferring a little of solution X into some of solution Y with a pipette. Manual pipetting is tedious, error prone, and very low throughput, but automated liquid handling workstations run into the hundreds of thousands of dollars. This makes [Urs Gaudenz]’s …read more
Cordless Drill Uses no Electricity
There are few projects on how to make your own cordless drill, but what sets [Johnnyq90’s] amazing project apart is the fact that his power plant is a nitro engine. Not an easy task of course, but he makes it look easier than it is, and we really enjoyed the construction process.
He uses an RC Kyosho GX12 engine that was previously modified, changing the cooling head with a larger one. The engine drives a gearbox that was taken from another drill. All other parts were hand made. The clutch was carefully machined, and the cooling fan was made in …read more
Autonomous Delivery: Your Impulse Buys Will Still Be Safe
I heard a “Year in Review” program the other day on NPR with a BBC World Service panel discussion of what’s ahead for 2017. One prediction was that UAV delivery of packages would be commonplace this year, and as proof the commentator reported that Amazon had already had a successful test in the UK. But he expressed skepticism that it would ever be possible in the USA, where he said that “the first drone that goes over somebody’s property will be shot down and the goods will be taken.”
He seemed quite sincere about his comment, but we’ll give him …read more
